Commutator for dynamo-electric machines



(No Model.)

H. F. PARSHALL.

GOMMUTATOR FOR DYNAMO ELECTRIC MACHINES.

No. 499,350. Patented June 13, 1893.

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UNITED STATES PATENT OFFICE.

HORACE F. PARSHALL, OF LYNN, MASSACHUSETTS, ASSIGNOR TO THE GENERAL ELECTRIC COMPANY, OF NE\V YORK.

COMMUTATOR FOR DYNAMO-ELECTRIC MACHINES.

SPECIFICATION forming part of Letters Patent No. 499,350, dated June 13, 1893.

Application filed January 13, 1893- Serial No- 4:58l3O7' (N0 model-l To all whom it may concern.-

Be it known that I, HORACE F. PARSHALL, a citizen of the United States, residing at Lynn, in the county of Essex and State of Massachusetts, have invented a new and useful Improvement in Commutators forDynamo-Electrio Machines, of which the following is a specification.

My invention relates to dynamo-electric machines, its object being to provide a commutator Which may be readily renewed segment by segment as the contact surface wears away and becomes uneven, and also to furnish segments stiff enough to withstand the centrifugal force due to the high rate of speed at which the commutator revolves. Copper is also saved, and by employing a cheaper metal when such metal will do as well if not better, great saving in cost is effected. In commutators as usually constructed each segment is made entirely of copper, and all are clamped to the armature shaft in such a manner that one cannot be removed withoutloosening the whole. This is a source of considerable trouble when there is need of renewing one or more segments, as the commutator has to be entirely taken apart and reassembled when the necessary repairs have been made. Moreover in large machines, while it is quite essential that the contact surface and connections shall be of copper, it is desirable to have a segment stronger and stiffer as well as less expensive than one made wholly of that material. These ends I attain by making a segment in two parts dovetailed together, the contact portion being of copper or other good conducting metal, and the lower or base portion of rolled steel oranysuitable material of greater strength and less cost than that composing the contact surface. These segments are then clamped to the armature shaft by a series of clamping-pieces bolted together in pairs, each of which pairs may hold one or more segments.

In the accompanying drawings, Figure 1 is a side View, partly in section and partly in elevation, of a commutator constructed in accordance with my invention. Fig. 2 is an end View of the same, also partly in section and partly in elevation. Figs. 3 and 4 are details showing different methods of dovetailing together the two parts of a segment.

Referring to Fig. 1 of the drawings, thearmature shaft A is provided with a collar B keyed or otherwise fastened thereon, upon which the segments of the commutator are supported. The segments themselves are made in separate parts C and C composed respectively of rolled steel or other material of sufficient rigidity, and copper. These two portions are jointed together, preferably as shown in Fig. 2, although they may be otherwise dovetailed in any suitable way, as shown, for example, in Figs. 3 and t. The portion C or contact-portion of each segment is provided with an arm or extension C", integral therewith or secured in good electrical connection thereto, through which connection is made with the coils of the armature. The lower portion C of the segmentismadelonger than the upper or contact-portion, and is extended in the arms 0, c, which are engaged by the clamps D D hereinafter described.

The method of assembling the commutator is as follows: Then one or any desired number of segments, properly insulated one from another, have been placed in position upon the insulated collar or base portion B, the clamping-pieces D D are applied, which engage respectively with the upper sides of the extensions 0, c, and the upper surfaces of annular grooves B in the collar or base-portion B. Through these clamping-pieces from one to the other of each pair pass bolts B which also pass through holes in the base-portion B bored to receive them. The said base-portion is preferably made, as shown in Fig. 1, with flanges 1) around its circumference, upon which the segments rest and through which the clamping bolts pass. The inner portion of the clam ping-piece above described, which engages with the annular groove in the baseportion 13, is cut on a bevel, and that portion of the said groove engaged by said clampingpiece is correspondingly beveled, so that as 9 the clamping-pieces are forced into the grooves by the bolts 13 and nuts 13, the wedging action of the two beveled edges forces the clamping-pieces firmly down upon the projections c, c of the segments, clamping them in place. In the drawings each pair of clamping pieces is represented as embracing four segments and held in place by two bolts, but it is obvious that a separate pair of clamps might be used for each segment or each two or more segments, and be provided with one, two or more bolts, as found expedient. After all the segments and clamps are in place, the spaces E between the clamps and the segments may be filled, in order to give a more finished look to the commutator, with plaster of paris or other plastic, insulating material, which can be readily broken away for repairs and as readily replaced after the repairs are made.

In a commutator of this description, at segment or segments may be removed without disturbing any others except those which may be engaged by the same pair of clamps; and the contact surfaces C can be replaced, if need be, and the segment returned. A considerable saving is thus effected in the cost of repairs, as well as in the first cost of the commutator, while a more rigid segment of effieient conductivity is secured.

\Vhat I claim as new, and desire to secure by Letters Patent, is-

1. A commutator-segment comprising a base-portion of one metal and a contact-portion of another better conductingmetal dovetailed thereto, as described.

2. A commutatorsegment comprising a base-portion of metal selected for strength, adapted to be clamped upon a commutatorbase or armature shaft, and a removable contact-portion of metal selected for conductivity dovetailed thereto, substantially as described.

0. A commutatorsegment comprising a base-portion of steel or like metal of superior strength but relatively inferior conductivity, and a contact-portion of copper, said baseand contact-portions being fitted together, so that the contact-portion is given a firm bearing upon the base portion for the resistance of displacement by centrifugal action when in use, substantially as set forth.

4. In a commutator, the device for holding in place the segments thereof, comprising the beveled clamping-pieces D D, correspondingly beveled grooves in the sides of the commutator-base B engaged thereby, and bolts and nuts adapted to force said clampingpieces into engagement with said beveled grooves, substantially as and for the purpose described. I

'5. In a commutator, the combination with an annular base-portion, of segment bases clamped singly or in groups thereon, and removable contact-portions dovetailed to said segment-bases, as described.

6. In a commutator, the combination with abase-portion B, of segment-bases supported thereon, contact-portions dovetailed to said segment-bases, beveled grooves in said baseportion B, clamping-pieces adapted to engage respectively with said segment-bases and said beveled grooves, and bolts and nuts adapted to actuate and secure said clamping-pieces, substantially as described.

In witness whereof I have hereunto set my hand this 2d day of January, 1893.

HORACE F. PARSIIALL.

Witnesses:

JOHN W. GIBBONEY, BENJAMIN B. IIULL. 

